use std::pin::Pin;
use std::task::{Context, Poll};
use std::{fmt, io};
use bytes::{Buf, BytesMut};
use futures_core::{ready, Stream};
use futures_sink::Sink;
use crate::{AsyncRead, AsyncWrite, Decoder, Encoder};
/// Low-water mark
const LW: usize = 1024;
/// High-water mark
const HW: usize = 8 * 1024;
bitflags::bitflags! {
struct Flags: u8 {
const EOF = 0b0001;
const READABLE = 0b0010;
}
}
pin_project_lite::pin_project! {
/// A unified `Stream` and `Sink` interface to an underlying I/O object, using
/// the `Encoder` and `Decoder` traits to encode and decode frames.
///
/// Raw I/O objects work with byte sequences, but higher-level code usually
/// wants to batch these into meaningful chunks, called "frames". This
/// method layers framing on top of an I/O object, by using the `Encoder`/`Decoder`
/// traits to handle encoding and decoding of message frames. Note that
/// the incoming and outgoing frame types may be distinct.
pub struct Framed<T, U> {
#[pin]
io: T,
codec: U,
flags: Flags,
read_buf: BytesMut,
write_buf: BytesMut,
}
}
impl<T, U> Framed<T, U>
where
T: AsyncRead + AsyncWrite,
U: Decoder,
{
/// This function returns a *single* object that is both `Stream` and
/// `Sink`; grouping this into a single object is often useful for layering
/// things like gzip or TLS, which require both read and write access to the
/// underlying object.
pub fn new(io: T, codec: U) -> Framed<T, U> {
Framed {
io,
codec,
flags: Flags::empty(),
read_buf: BytesMut::with_capacity(HW),
write_buf: BytesMut::with_capacity(HW),
}
}
}
impl<T, U> Framed<T, U> {
/// Returns a reference to the underlying codec.
pub fn codec_ref(&self) -> &U {
&self.codec
}
/// Returns a mutable reference to the underlying codec.
pub fn codec_mut(&mut self) -> &mut U {
&mut self.codec
}
/// Returns a reference to the underlying I/O stream wrapped by
/// `Frame`.
///
/// Note that care should be taken to not tamper with the underlying stream
/// of data coming in as it may corrupt the stream of frames otherwise
/// being worked with.
pub fn io_ref(&self) -> &T {
&self.io
}
/// Returns a mutable reference to the underlying I/O stream.
///
/// Note that care should be taken to not tamper with the underlying stream
/// of data coming in as it may corrupt the stream of frames otherwise
/// being worked with.
pub fn io_mut(&mut self) -> &mut T {
&mut self.io
}
/// Returns a `Pin` of a mutable reference to the underlying I/O stream.
pub fn io_pin(self: Pin<&mut Self>) -> Pin<&mut T> {
self.project().io
}
/// Check if read buffer is empty.
pub fn is_read_buf_empty(&self) -> bool {
self.read_buf.is_empty()
}
/// Check if write buffer is empty.
pub fn is_write_buf_empty(&self) -> bool {
self.write_buf.is_empty()
}
/// Check if write buffer is full.
pub fn is_write_buf_full(&self) -> bool {
self.write_buf.len() >= HW
}
/// Check if framed is able to write more data.
///
/// `Framed` object considers ready if there is free space in write buffer.
pub fn is_write_ready(&self) -> bool {
self.write_buf.len() < HW
}
/// Consume the `Frame`, returning `Frame` with different codec.
pub fn replace_codec<U2>(self, codec: U2) -> Framed<T, U2> {
Framed {
codec,
io: self.io,
flags: self.flags,
read_buf: self.read_buf,
write_buf: self.write_buf,
}
}
/// Consume the `Frame`, returning `Frame` with different io.
pub fn into_map_io<F, T2>(self, f: F) -> Framed<T2, U>
where
F: Fn(T) -> T2,
{
Framed {
io: f(self.io),
codec: self.codec,
flags: self.flags,
read_buf: self.read_buf,
write_buf: self.write_buf,
}
}
/// Consume the `Frame`, returning `Frame` with different codec.
pub fn into_map_codec<F, U2>(self, f: F) -> Framed<T, U2>
where
F: Fn(U) -> U2,
{
Framed {
io: self.io,
codec: f(self.codec),
flags: self.flags,
read_buf: self.read_buf,
write_buf: self.write_buf,
}
}
}
impl<T, U> Framed<T, U> {
/// Serialize item and Write to the inner buffer
pub fn write<I>(mut self: Pin<&mut Self>, item: I) -> Result<(), <U as Encoder<I>>::Error>
where
T: AsyncWrite,
U: Encoder<I>,
{
let this = self.as_mut().project();
let remaining = this.write_buf.capacity() - this.write_buf.len();
if remaining < LW {
this.write_buf.reserve(HW - remaining);
}
this.codec.encode(item, this.write_buf)?;
Ok(())
}
/// Try to read underlying I/O stream and decode item.
pub fn next_item(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<Result<<U as Decoder>::Item, U::Error>>>
where
T: AsyncRead,
U: Decoder,
{
loop {
let mut this = self.as_mut().project();
// Repeatedly call `decode` or `decode_eof` as long as it is
// "readable". Readable is defined as not having returned `None`. If
// the upstream has returned EOF, and the decoder is no longer
// readable, it can be assumed that the decoder will never become
// readable again, at which point the stream is terminated.
if this.flags.contains(Flags::READABLE) {
if this.flags.contains(Flags::EOF) {
match this.codec.decode_eof(&mut this.read_buf) {
Ok(Some(frame)) => return Poll::Ready(Some(Ok(frame))),
Ok(None) => return Poll::Ready(None),
Err(e) => return Poll::Ready(Some(Err(e))),
}
}
log::trace!("attempting to decode a frame");
match this.codec.decode(&mut this.read_buf) {
Ok(Some(frame)) => {
log::trace!("frame decoded from buffer");
return Poll::Ready(Some(Ok(frame)));
}
Err(e) => return Poll::Ready(Some(Err(e))),
_ => (), // Need more data
}
this.flags.remove(Flags::READABLE);
}
debug_assert!(!this.flags.contains(Flags::EOF));
// Otherwise, try to read more data and try again. Make sure we've got room
let remaining = this.read_buf.capacity() - this.read_buf.len();
if remaining < LW {
this.read_buf.reserve(HW - remaining)
}
let cnt = match tokio_util::io::poll_read_buf(this.io, cx, this.read_buf) {
Poll::Pending => return Poll::Pending,
Poll::Ready(Err(e)) => return Poll::Ready(Some(Err(e.into()))),
Poll::Ready(Ok(cnt)) => cnt,
};
if cnt == 0 {
this.flags.insert(Flags::EOF);
}
this.flags.insert(Flags::READABLE);
}
}
/// Flush write buffer to underlying I/O stream.
pub fn flush<I>(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), U::Error>>
where
T: AsyncWrite,
U: Encoder<I>,
{
let mut this = self.as_mut().project();
log::trace!("flushing framed transport");
while !this.write_buf.is_empty() {
log::trace!("writing; remaining={}", this.write_buf.len());
let n = ready!(this.io.as_mut().poll_write(cx, this.write_buf))?;
if n == 0 {
return Poll::Ready(Err(io::Error::new(
io::ErrorKind::WriteZero,
"failed to write frame to transport",
)
.into()));
}
// remove written data
this.write_buf.advance(n);
}
// Try flushing the underlying IO
ready!(this.io.poll_flush(cx))?;
log::trace!("framed transport flushed");
Poll::Ready(Ok(()))
}
/// Flush write buffer and shutdown underlying I/O stream.
pub fn close<I>(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Result<(), U::Error>>
where
T: AsyncWrite,
U: Encoder<I>,
{
let mut this = self.as_mut().project();
ready!(this.io.as_mut().poll_flush(cx))?;
ready!(this.io.as_mut().poll_shutdown(cx))?;
Poll::Ready(Ok(()))
}
}
impl<T, U> Stream for Framed<T, U>
where
T: AsyncRead,
U: Decoder,
{
type Item = Result<U::Item, U::Error>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
self.next_item(cx)
}
}
impl<T, U, I> Sink<I> for Framed<T, U>
where
T: AsyncWrite,
U: Encoder<I>,
U::Error: From<io::Error>,
{
type Error = U::Error;
fn poll_ready(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
if self.is_write_ready() {
Poll::Ready(Ok(()))
} else {
Poll::Pending
}
}
fn start_send(self: Pin<&mut Self>, item: I) -> Result<(), Self::Error> {
self.write(item)
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.flush(cx)
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.close(cx)
}
}
impl<T, U> fmt::Debug for Framed<T, U>
where
T: fmt::Debug,
U: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Framed")
.field("io", &self.io)
.field("codec", &self.codec)
.finish()
}
}
impl<T, U> Framed<T, U> {
/// This function returns a *single* object that is both `Stream` and
/// `Sink`; grouping this into a single object is often useful for layering
/// things like gzip or TLS, which require both read and write access to the
/// underlying object.
///
/// These objects take a stream, a read buffer and a write buffer. These
/// fields can be obtained from an existing `Framed` with the `into_parts` method.
pub fn from_parts(parts: FramedParts<T, U>) -> Framed<T, U> {
Framed {
io: parts.io,
codec: parts.codec,
flags: parts.flags,
write_buf: parts.write_buf,
read_buf: parts.read_buf,
}
}
/// Consumes the `Frame`, returning its underlying I/O stream, the buffer
/// with unprocessed data, and the codec.
///
/// Note that care should be taken to not tamper with the underlying stream
/// of data coming in as it may corrupt the stream of frames otherwise
/// being worked with.
pub fn into_parts(self) -> FramedParts<T, U> {
FramedParts {
io: self.io,
codec: self.codec,
flags: self.flags,
read_buf: self.read_buf,
write_buf: self.write_buf,
}
}
}
/// `FramedParts` contains an export of the data of a Framed transport.
/// It can be used to construct a new `Framed` with a different codec.
/// It contains all current buffers and the inner transport.
#[derive(Debug)]
pub struct FramedParts<T, U> {
/// The inner transport used to read bytes to and write bytes to
pub io: T,
/// The codec
pub codec: U,
/// The buffer with read but unprocessed data.
pub read_buf: BytesMut,
/// A buffer with unprocessed data which are not written yet.
pub write_buf: BytesMut,
flags: Flags,
}
impl<T, U> FramedParts<T, U> {
/// Create a new, default, `FramedParts`
pub fn new(io: T, codec: U) -> FramedParts<T, U> {
FramedParts {
io,
codec,
flags: Flags::empty(),
read_buf: BytesMut::new(),
write_buf: BytesMut::new(),
}
}
/// Create a new `FramedParts` with read buffer
pub fn with_read_buf(io: T, codec: U, read_buf: BytesMut) -> FramedParts<T, U> {
FramedParts {
io,
codec,
read_buf,
flags: Flags::empty(),
write_buf: BytesMut::new(),
}
}
}